text: Zn isotope ratios vary between individual blood components, bones and the different organs in humans, though in general, δZn values fall within a narrow range. In the blood of healthy individuals, the Zn isotopic composition of erythrocytes is typically ~0.3‰ lighter than that of serum, and no significant differences in erythrocyte or serum δZn values exist between men and women. For example, in the blood of 49 healthy blood donors, the average erythrocyte δZn value was +0.44 ± 0.33‰, while that of serum was +0.17 ± 0.26‰. In a separate study on 29 donors, a similar average δZn value of +0.29 ± 0.27‰ was obtained for the patients' serum. Additionally, in a small sample set of volunteers, whole blood δZn values were ~+0.15‰ higher for vegetarians than for omnivores, suggesting diet plays an important role in driving Zn isotope compositions in the human body.